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The article presents the results of research of two spin-injection sources of THz radiation using different structures of thin-film magnetic transitions (MT) with antiferromagnetic (AFM) FeMn film of nanoscale thickness and ferromagnetic (FM) Fe layer. In both variants, the possibility of intrinsic magnetization forming in the AFM film under the action of a spin-polarized current of a relatively small value formed in the FM layer is shown. The physical foundations of this effect based on the AFM sublattices beveling by a spin-polarized current due to the sd-exchange interaction of the conduction electrons spins with the spins of d electrons of the FM crystal lattice are considered. This does not require an external magnetic field. sd-exchange mechanism of excitation of intrinsic magnetization in AFM is an alternative to the spin-orbit mechanism, which has been widely considered recently. The relations for calculating the frequency and power of spin-injection radiation are given. New experimental results have been obtained that develop the concept of the AFM's intrinsic magnetization. The non-thermal nature of spin-injection radiation and the possibility of increasing the efficiency of the emitter operation due to the ordering of the MT structure by an external magnetic field are shown. The way of increasing the efficiency of spin-injection emitters by creating structures with multiple independently operating micro-emitters at frequencies close to 16 THz and with a signal power of up to a hundred microwatts has been determined. In general, it is shown that the use of the effect of excitation of intrinsic magnetization in AFM is of interest, both from the point of view of the development of theoretical ideas about the magnetic properties of AFM, and from a practical point of view for the creation of spin-injection lasers (tasers).

The paper presents the experimental study results for the ultrawideband microwave oscillator on the chip-elements and Si-Ge transistor. To increase the efficiency modes the passive nonlinear contour is used. It is shown, that the given system forms chaotic oscillations in the given frequency band with efficiency of∼ 8 %.

In this work the authors present a thorough experimental study of a practical realization of a complex analog signal transmission system using dynamic chaos. It is demonstrated that the chaotic synchronous response could be used as a basis for the design of secure communication channels. The results presented in this work confirm the possibility of secure wireless communications in RF band, while they allow the authors to analyze in detail the restrictions and problems connected with the quality of synchronization of the transmitter and the receiver of the wireless communication systems. The effect of the perturbing factors on the transmission quality is investigated theoretically. It is shown that the main reason of the transmission’s quality degradation is the chaotic response desynchronization associated with the phenomenon of “on-off” intermittency. It is found that under the effect of the perturbing factors, the level of information signal fed to the transmitter must be increased in order to obtain qualitative information transmission. However, in order to provide secure communication, one must decrease the information signal level. A compromise on these contradictory requirements provides an improvement of the quality of the synchronous chaotic response in the receiver.

The problem of positioning using UWB chaotic radio pulses is considered. Differential time of arrival method based on cross-correlation function of chaotic radio pulse envelope signals is proposed and investigated. It is shown that the proposed approach provides accurate estimation of time difference of arrival, proportional to the envelope signal frequency bandwidth. Immunity of the proposed method to noise increases with the duration of chaotic radio pulse.

In this report the problem of forming chaotic signals with prescribed spectrum is discussed. Possibilities of chaotic spectrum control in band-limited chaotic oscillator are demonstrated. Dependence of the form and ruggedness of chaotic spectrum on system parameters is shown.

An approach to the design of chaotic oscillators with controlled bandwidth in different frequency bands is proposed. Mathematical models of the oscillator and simulation results are considered. Implementations of microwave chaotic oscillators and experimental results are demonstrated.

A method to create dynamic models of microwave transistor systems is described. In systems with inertia, exhibiting regular and complicated dynamics, evolution of the auto-oscillation process depends both on the connection of inertial chain and on the type of dynamic characteristics of the nonlinear amplification element. These systems may be used in dynamic models of microwave transistor systems, which are inertial and consist of nonlinearities. The analysis shows that a global chaotization of oscillations in the system studied is preceded by a sequence of bifurcations according to the natural scale law, whereby zones of stable motion alternate with zones of chaotic motion.

The theoretical opportunity of creating chaotic generators is also investigated experimentally on the basis of two or more coupled one-transistor generators in the microwave range. The paper reports the design of transistor microwave oscillators in which it is possible to control the frequency band and the spectral characteristic is smooth. We show that the use of two and three coupled transistor auto-oscillators allows us to create microwave chaotic wide-band generators.